The invention relates to a method for automatic user adaptation of the stimulus characteristic of an active operator control element of a vehicle and an arrangement for implementation of the method.
While passive operator control elements due to their structural design can only provide passive feedback through their actuation haptics, active operator control elements are characterized by the fact that they can, unlike passive operator control elements, transmit tactually perceptible information to the user in the form of a stimulus via force or movement changes, depending on the situation. This force or movement change of active operator control elements is generated by actuation information, with which the active operator control element is actuated. This actuation information is referred to here as a stimulus characteristic.
Active operator control elements are recently increasingly being used in the automotive industry. First to mention here are active vehicle pedals and active steering wheels. Both are designed so that they either generate, dependent on the driving situation, a reaction force which is tactually perceptible by the operator and which opposes the operating force, or they generate, dependent on the driving situation, an oscillation in the actuating element which is tactually perceptible by the operator. In the first case, an actuator generating the opposing force is provided in the mechanics of the actuating element, in the second case, an oscillation generator is provided which applies to the operating element mechanical oscillations of preset frequency and amplitude. Such active operator control elements are usually used in conjunction with so-called assistance systems that serve to assist the driver in avoiding undesirable driving situations and/or operating situations. In the context of the facts discussed herein, such undesired driving situation and/or operating situation of the vehicle occurs when the operator has caused this particular undesirable driving situation and/or operating situation through the degree of actuation of the active operator control element and/or when the undesirable driving condition and/or operating situation can be reversed into a normal state by a change in the current degree of actuation of the active operator control element.
If, for example, a driver has approached with his vehicle an impending spin of the drive wheels due to excessive actuation of the accelerator pedal, a vehicle control unit equipped with a stability system can detect the impending spin of the wheels by evaluating corresponding sensor values and signal to the driver to step off the gas by building up a force opposing the actuating force of the accelerator pedal force. A vehicle control unit equipped with a lane departure warning assistance system can, for example, be designed such that it triggers, when leaving the lane, an oscillation generator which initiates oscillations in the steering wheel. In both cases, the driver is offered a tactually perceptible stimulus with a certain characteristic in order to avoid the undesired driving situation. Similarly, unwanted operating situations, for example the overspeeding of the engine, can be communicated tactually to the driver.
The examples mentioned above can be applied to many different driving situations and/or operating situations and to various operator control elements in such a way that pedals are caused to vibrate and a force opposing the steering force is applied to steering wheels.
Problematic in the choice of the intensity of the stimulus, i.e. the opposing force which is applied to the operator control element or the amplitude and frequency of the oscillation applied to the operator control element should meet two opposing requirements. On the one hand, tactual perception by the driver must be ensured; on the other hand, the strength of the tactual signal should not significantly affect the ride comfort.
In order to meet these contradictory requirements, it has already been proposed in DE 10 2010 010 400 A1 to make the force opposing the actuating force changeable in a pedal having a controllable damping element in such a way that this opposing force is increased compared to a basic value in a sport driving mode and decreased compared to a basic value in a comfort mode. Furthermore, the basic value should be adjustable by the driver.
Although the approach outlined here somewhat alleviates the problem of the choice of stimulus intensity, it requires, on the one hand, an active intervention from the driver, which in turn has a comfort-reducing effect and is associated with the aforementioned driving modes.
In DE 10 2007 032 310 A1 is proposed in conjunction with an active operating pedal of a commercial vehicle to design the adjustability of the opposing force by the operator such that the entire operating characteristic is customized and can be stored.
With this solution, too, a complex adjustment process by the operator is required, which may be adequate for agricultural machinery or construction machinery, but is not effective for passenger cars.
Furthermore, in DE 10 2011 088 266 A1 it is proposed, in order to avoid the manual adjustment of an opposing force generated by an accelerator pedal, to detect the weight of the driver and optionally his seating position via a driver's seat sensor. An opposing force is then set automatically depending on the detected variables.
Although this approach allows automatic adjustment of the generated opposing force, it is quite different from an individual setting, for example, because the differences between people of identical weight and, more importantly, the significant differences between experienced and inexperienced operators are not accounted for. Such an approach would always have to initially assume an inexperienced operator when selecting the opposing force who, as experiments have shown, requires for the perception of the perceptible tactual cues imparted by the accelerator pedal much larger opposing forces and/or amplitudes, i.e. completely different stimulus intensities, than for an operator familiar with the operation.
To overcome the disadvantages of the prior art, it is an object of the invention to provide a method and an arrangement for carrying out the method which makes it possible to automatically adjust the tactually perceptible stimulus intensity of an active operator control element for an operator individually, such that the stimulus, on the one hand, is dearly perceptible by the operator and, on the other hand, is selected so that the tactual perception of the stimulus is perceived by the operator as reducing the comfort only insignificantly.